全文获取类型
收费全文 | 131篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
现状及发展 | 18篇 |
研究方法 | 11篇 |
综合类 | 101篇 |
自然研究 | 2篇 |
出版年
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1997年 | 2篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 4篇 |
1966年 | 6篇 |
1965年 | 1篇 |
排序方式: 共有132条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
Gene regulation. Fingers and DNA half-turns 总被引:7,自引:0,他引:7
S C Harrison 《Nature》1986,322(6080):597-598
95.
96.
Materials science. The hardest known oxide 总被引:3,自引:0,他引:3
Dubrovinsky LS Dubrovinskaia NA Swamy V Muscat J Harrison NM Ahuja R Holm B Johansson B 《Nature》2001,410(6829):653-654
A material as hard as diamond or cubic boron nitride has yet to be identified, but here we report the discovery of a cotunnite-structured titanium oxide which represents the hardest oxide known. This is a new polymorph of titanium dioxide, where titanium is nine-coordinated to oxygen in the cotunnite (PbCl2) structure. The phase is synthesized at pressures above 60 gigapascals (GPa) and temperatures above 1,000 K and is one of the least compressible and hardest polycrystalline materials to be described. 相似文献
97.
DNA is wound tightly into phage heads in such a way that it tends to form layers concentric with the rigid protein shell. In P22 and wild-type lambda, DNA completely fills the internal volume, with a highly uniform local packing of adjacent segments; in lambda deletion mutants containing less than a full genome, the local packing distance increases correspondingly. 相似文献
98.
99.
EDRF coordinates the behaviour of vascular resistance vessels 总被引:4,自引:0,他引:4
Constriction of vascular smooth muscle in response to the stimulus of raised intravascular pressure--the myogenic response--represents a positive feedback mechanism which, if unopposed, could theoretically lead to instability in the intact circulation. Dilation in response to increased intraluminal flow would provide an opposing feedback mechanism which could confer overall stability. Flow-dependent dilation in conduit vessels is mediated by endothelium-derived relaxing factor (EDRF), but the relationship between flow and EDRF activity has not been studied in resistance vessels in situ. We here demonstrate that EDRF can coordinate the aggregate hydrodynamic properties of an intact network. Under control conditions, EDRF maintains a fourth-power relationship between diameter and flow so that the pressure gradient in each vessel asymptotically approaches a constant value at high flow rates. Basal EDRF release may also maintain a similar spatial distribution of flow at different flow rates, even under conditions of moderate pharmacological constriction. 相似文献
100.